[flang][lowering] Add lowering for the set_exponent intrinsic

This patch adds support for lowering of the `set_exponent` intrinsic
from Fortran to the FIR dialect of MLIR.

This is part of the upstreaming effort from the `fir-dev` branch in [1].

[1] https://github.com/flang-compiler/f18-llvm-project

Differential Revision: https://reviews.llvm.org/D121805

Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Eun Jung Park <ejpark@lanl.gov>

flang/lib/Lower/IntrinsicCall.cpp

@@ -26,6 +26,7 @@
 #include "flang/Optimizer/Builder/MutableBox.h"
 #include "flang/Optimizer/Builder/Runtime/Character.h"
 #include "flang/Optimizer/Builder/Runtime/Inquiry.h"
+#include "flang/Optimizer/Builder/Runtime/Numeric.h"
 #include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
 #include "flang/Optimizer/Builder/Runtime/Reduction.h"
 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
@@ -466,6 +467,8 @@ struct IntrinsicLibrary {
   void genRandomInit(llvm::ArrayRef<fir::ExtendedValue>);
   void genRandomNumber(llvm::ArrayRef<fir::ExtendedValue>);
   void genRandomSeed(llvm::ArrayRef<fir::ExtendedValue>);
+  mlir::Value genSetExponent(mlir::Type resultType,
+                             llvm::ArrayRef<mlir::Value> args);
   fir::ExtendedValue genSize(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genSum(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   void genSystemClock(llvm::ArrayRef<fir::ExtendedValue>);
@@ -668,6 +671,7 @@ static constexpr IntrinsicHandler handlers[]{
      &I::genRandomSeed,
      {{{"size", asBox}, {"put", asBox}, {"get", asBox}}},
      /*isElemental=*/false},
+    {"set_exponent", &I::genSetExponent},
     {"sum",
      &I::genSum,
      {{{"array", asBox},
@@ -2002,6 +2006,17 @@ void IntrinsicLibrary::genRandomSeed(llvm::ArrayRef<fir::ExtendedValue> args) {
   Fortran::lower::genRandomSeed(builder, loc, -1, mlir::Value{});
 }
 
+// SET_EXPONENT
+mlir::Value IntrinsicLibrary::genSetExponent(mlir::Type resultType,
+                                             llvm::ArrayRef<mlir::Value> args) {
+  assert(args.size() == 2);
+
+  return builder.createConvert(
+      loc, resultType,
+      fir::runtime::genSetExponent(builder, loc, fir::getBase(args[0]),
+                                   fir::getBase(args[1])));
+}
+
 // SUM
 fir::ExtendedValue
 IntrinsicLibrary::genSum(mlir::Type resultType,

flang/test/Lower/Intrinsics/set_exponent.f90

@@ -0,0 +1,47 @@
+! RUN: bbc -emit-fir %s -o - | FileCheck %s
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck %s
+
+! SET_EXPONENT
+! CHECK-LABEL: set_exponent_test
+subroutine set_exponent_test
+
+  real(kind = 4) :: x1 = 178.1378e-4
+  real(kind = 8) :: x2 = 178.1378e-4
+  real(kind = 10) :: x3 = 178.1378e-4
+  real(kind = 16) :: x4 = 178.1378e-4
+  integer :: i = 17
+! CHECK: %[[addri:.*]] = fir.address_of(@_QFset_exponent_testEi) : !fir.ref<i32>
+! CHECK: %[[addrx1:.*]] = fir.address_of(@_QFset_exponent_testEx1) : !fir.ref<f32>
+! CHECK: %[[addrx2:.*]] = fir.address_of(@_QFset_exponent_testEx2) : !fir.ref<f64>
+! CHECK: %[[addrx3:.*]] = fir.address_of(@_QFset_exponent_testEx3) : !fir.ref<f80>
+! CHECK: %[[addrx4:.*]] = fir.address_of(@_QFset_exponent_testEx4) : !fir.ref<f128>
+
+  x1 = set_exponent(x1, i)
+! CHECK: %[[x1:.*]] = fir.load %[[addrx1:.*]] : !fir.ref<f32>
+! CHECK: %[[i1:.*]] = fir.load %[[addri:.*]] : !fir.ref<i32>
+! CHECK: %[[i64v1:.*]] = fir.convert %[[i1:.*]] : (i32) -> i64
+! CHECK: %[[result1:.*]] = fir.call @_FortranASetExponent4(%[[x1:.*]], %[[i64v1:.*]]) : (f32, i64) -> f32
+! CHECK: fir.store %[[result1:.*]] to %[[addrx1:.*]] : !fir.ref<f32>
+
+  x2 = set_exponent(x2, i)
+! CHECK: %[[x2:.*]] = fir.load %[[addrx2:.*]] : !fir.ref<f64>
+! CHECK: %[[i2:.*]] = fir.load %[[addri:.*]] : !fir.ref<i32>
+! CHECK: %[[i64v2:.*]] = fir.convert %[[i2:.*]] : (i32) -> i64
+! CHECK: %[[result2:.*]] = fir.call @_FortranASetExponent8(%[[x2:.*]], %[[i64v2:.*]]) : (f64, i64) -> f64
+! CHECK: fir.store %[[result2:.*]] to %[[addrx2:.*]] : !fir.ref<f64>
+
+  x3 = set_exponent(x3, i)
+! CHECK: %[[x3:.*]] = fir.load %[[addrx3:.*]] : !fir.ref<f80>
+! CHECK: %[[i3:.*]] = fir.load %[[addri:.*]] : !fir.ref<i32>
+! CHECK: %[[i64v3:.*]] = fir.convert %[[i3:.*]] : (i32) -> i64
+! CHECK: %[[result3:.*]] = fir.call @_FortranASetExponent10(%[[x3:.*]], %[[i64v3:.*]]) : (f80, i64) -> f80
+! CHECK: fir.store %[[result3:.*]] to %[[addrx3:.*]] : !fir.ref<f80>
+
+  x4 = set_exponent(x4, i)
+! CHECK: %[[x4:.*]] = fir.load %[[addrx4:.*]] : !fir.ref<f128>
+! CHECK: %[[i4:.*]] = fir.load %[[addri:.*]] : !fir.ref<i32>
+! CHECK: %[[i64v4:.*]] = fir.convert %18 : (i32) -> i64
+! CHECK: %[[result4:.*]] = fir.call @_FortranASetExponent16(%[[x4:.*]], %[[i64v4:.*]]) : (f128, i64) -> f128
+! CHECK: fir.store %[[result4:.*]] to %[[addrx4:.*]] : !fir.ref<f128>
+end subroutine set_exponent_test
+